Certain conditions, such as hypertension, diabetes, hemophilia and other chronic conditions, can be especially taxing because they require ongoing therapeutic intervention. In many instances, patients can suffer not only the inconvenience caused by exceedingly frequent drug administration, but can also risk regular exposure to both toxic and ineffective plasma levels of drugs; toxic levels occurring soon after the drug is administered and ineffective levels occurring prior to the next scheduled administration.
Efforts have been directed toward development of controlled-release preparations such as matrixes, coated granules, or microcapsules. In addition, systems for delivery of a certain amount of drug per unit time have been developed. Systems that release drugs at a constant rate (zero-order drug delivery) are known.
One type of delivery system uses on an infusion pump for drug delivery.